Refrigeration applicator



March 4, 1958 .1. D. MGGEE REFRIGERATION APPLICATOR Filed Aug. 51, 1956bin/EMT;

2,825,339 I REFRIGERATION APPLIYCATOR James D. McGee, London, EnglandApplication August 31, 1956, Serial No. 607,319 9 Claims. or. 128-403)This invention relates to an instrument for applying refrigeration tolocalized areas, e. g. to the human skin, and which may therefore betermed a refrigeration applicator.

In medical practice it is often desirable to apply very low temperaturesto local areas of the skin for the purpose of removing warts, moles orsimilar undesirable skin blemishes. The local freezing of the tissuesresults in the destruction of the unwanted cells. This is usually doneby applying a stick about /1 in diameter of compacted carbon dioxidesnow, at at temperature of about -80 C. to the unwanted object.

Alternatively a slush made by mixing carbon dioxide snow with acetone issometimes used, or even liquid nitrogen or liquid oxygen.

The use of such refrigerants has the following disadvantages:

(1) A stick of carbon dioxide snow compressed by a plunger in a plasticcylinder is blunt and may cover a larger area of skin than it is wishedto treat. This difficulty can be overcome by having a number ofcompression cylinders of different diameters; or the stick can besharpened by applying it with rotation on its axis to a metal surface; acone or truncated cone of snow results.

(2) A stick of carbon dioxide snow slowly diminishes in diameter whilebeing used, whether it be a cylinder, a truncated cone, or a cone. Thisloss of diameter through evaporation can be lessened by applying thestick in a plastic cylinder without extruding it from the end of thecylinder. This entails loss of visual control and loss of pressure onthe skin because it is difiicult to maintain steadypressnre equally onthe cylinder and on the snow contained in it. The plunger must bepressed in gradually as the snow evaporates.

(3) If the stick is applied with pressure to an area of skin of uniformconsistency while it is extruding from the compression cylinder, it willcause freezing of an indented disc of skin; the walls of the indentationalso become frozen and an unnecessarily large area of skin may blisteras a result.

(4) Carbon dioxide snow-acetone slush is not easy to manipulate. Appliedto a camel hair brush or by means of a cottonwool tipped woodenapplicator, it may accidentally be dropped on to an area of skin it isnot wished to treat, with painful and embarrassing results. If themixture drops on to rayon clothing solution of the cellulose acetateresults.

(5) It is difiicult to apply carbon dioxide slush accurately to smalllesions. This is also true of liquid nitrogen and liquid oxygen whichhave to be applied with a cotton-wool tipped applicator.

(6) The quantity of refrigerant conveniently prepared quickly vaporisesso that normally only one application is possible.

Attempts to make applicators have not heretofore overcome thesedifiiculties.

A United States Patent C ice According to the present invention anapplicator comprises two glass tubes one within the other, the innertube being open at both ends and the other tube being sealed to theinner tube at spaced positions to form a sealed space between the tubeswhich is substantially evacuated.

The refrigerant can be fed into one end of the inner tube, and pressedout of the other or application end or a metal heat conductor may beprovided in the inner tube and which extends out of the application endof the latter. in either arrangement the evacuated space holds therefrigerant at its low temperature for comparatively long periods,facilitates holding and applying of the applicator, and enables the userto effect close control of the area being treated.

The invention will now be further described by way of example withreference to the accompanying diagrammatic drawings wherein:

Figure l is a sectional view of an applicator made in accordance withthe invention; and

Figure 2 is a view on a larger scale of part of Figure 1.

in the construction shown in Figures 1 and 2 an inner tube It} islocated concentrically within an outer glass.

glass 11. These tubes are of round section and are made of a glasssuitable for withstanding high and low temperatures within minimumtendency to crack. At the application end, the inner tube is tapered at12 to a neck' 13 of reduced diameter at its end. At its other end theinner tube is formed with an outwardly extending flange 15 at such anangle that it forms a funnel to facilitate filling of refrigerant intothe tube. The outer tube is spaced from the inner tube and itsapplication and is tapered and sealed by fusing it at 17 to the end ofthe inner tube. The other end of the outer tube is formed with anoutwardly extending flange 18 which is at to the axis of the tubes.Although 90 is preferred a slightly less angle of from 85 to could betolerated. The flange 13 has the important function of providing someresilience for accommodating diiferential expansion or contraction ofthe tubes 10, 11 to avoid cracking the The flange 18 carries a tubularextension 19 at its outer edge and thi extension is fused to the flange15 at 213. A space 21 is thus sealed olf between the positions 17, 2%}that are spaced apart along the inner tube and this space is evacuatedand sealed at nipple 22. The joints 17, 20 could be at places other thanthose shown.

A metal conductor is provided consisting of a tube 25 having a solid end26. This conductor is made of an efiiciently heat-conducting metal suchas copper or silver. The tube fits with a tight push fit in the innerglass tube so that it does not loosen when at a low temperature. Thesolid end 26 is tapered down to a neck of small diameter at its end thatpasses out of the end of the tube 10 and has a wire ring 25 soldered toit to prevent axial movement of the conductor in the tube 10. The latterhas an inwardly extending projection 30 which engages in a depression inthe part 26 to prevent rotary movement of the conductor in the tube 10.The part 26 has a formation consisting of a tapped hole 32 into whichthe screwed stem 34 of any of a series of buttons 33 can be engaged.These buttons will be of various sizes and the button will be selectedaccording to the area to be treated.

The funnel 15 after insertion of the refrigerant may be closed with acotton wool or other packing 35 and a cap 36 of metal, polythene orother suitable material.

In operation, a charge of CO snow, or CO snow and acetone slush ofliquid nitrogen or of liquid oxygen is filled into the inner metalcylinder. A good deal will volatilize or boil off in cooling the innermetal and glass parts down to the very low temperatures of the refrig-'35 which must, however bes o" designed as ,toallow some escape-tot thevapourizing refrigerant, and; with the cap Because of the very efiicient conduction of heat by the metal sleeve 2 5, the protruding metal stubor' 'neck 26 is kept verynear the temperature of the refrigerant fillingthe cylinder 25. When thisfstub'is brought into contact with thewarm'skin' the heat is conducted awaysuificiently of outwardly extendingflanges.

' 3. An applicator as claimed in'claim l whe rein the connection betweenthe tubes. at one" end includes 4. An applicator as claimed in claim.3wherein at least one of the flanges is at an angle of from 85 to 951 tothe axis of the tubes. 7

rapidly to pause freezing of the underlying skin. However; becausecf thevacuum 'shellsurrounding the cylinder;25, the outer wall 11 is 'net'uncomfortably coldfand project out of one end of the inner tube; V r a 77 r J 8. An applicator asclaimed: in claim 7 wherein the:

5. An applicator as claimed in claim 3lwhereinlone flange'forms an inletfunnel for the inner tube.

6. An applicator as claimed in claim'l wherein the; i

application end of the outer tube is'tapered. i

7. An applicator as claimed in claim 1 wherein 'a metal as to;

heat conductor is mounted in the inner tube so metal conductor is a tubehaving 'a'tight fit in the inner '7 glass tube, saidrmetal tube being"open at one end and canbeliandled without disccmfortg Moreover, sinceheat j tive for a considerable time, e. g. 30 to 60 minutes, de: pendingon circumstances, afterjbeing iilled with a charge of CO2 snow Whileanyof the refrigerant remains in the instrument the temperature of theapplicator remains constant. Only when the refrigerant has alldisappeared will the applicator begin to slowly return to roomtemperature. ,Whcn not inruse the lower end on the instrument. should becovered witha rubber cap to minimize condensation of Water vapour andloss of cold by contact of the stub with the warm air.

I claim: a V a v a l. A refrigeration applicator comprising two glasstubes one within the other, the inner tube being open at both icarinotjenter' the instrument at all readily except through t the inetalstub or neck 26, the instrument remains operaends and the other. tubebeing sealed to the inner tube, 1

at spaced positions, to form a sealed space between the tubes whichsubstantially evacuated, and a metal heat conductor mounted in the innertube so as to project 7 out of one end of the inner tube.

2. An applicator as claimed in claim 1 wherein one end of the inner tubeis larger than thev other and the spaced positions are the ends of thetubes.

solid at its other end where it is of reduced diameter 7 I and projectsthroughjthe opcnend of the innerjglass' tube; 2' '9'. -An applicator as:claimed in claim 7 whereinjthe; metal conductor'is a tube having atight'fi't inthe: inner 1 glass tube, said metaltube being open at oneend and; 7

solid at its other end where it is of reduced diameter and projectsthrough the open end ofthe inner glass .tube, and wherein the'metal tubeis pr'evented from rotating. in the inner glass tube by a projection onone'of these tubes engaging a depression in the other, and a wire ring Vsoldered to the projecting end of the metal conductor prevents relativeaxial movement between the lattertand the inner glass tube.

References Cited in the file of, this patent UNITED STATES PATENTS 2,305,367 2,387,258

OTHER REFERENCES,

The .Lancet, for Aug. 11, in Scientific Library.)

Webb Dec. 15,1942 Hague Oct. 23', 1945 1956, pp. 290-91; (Copy:

